Disposable diaper and a method of manufacturing a disposable diaper

ABSTRACT

A disposable diaper includes a skin-surface side sheet; a non-skin surface side sheet; an absorber; and a waistline retaining unit. Leg stretching units are arranged in the inner side in a longitudinal direction from diaper ends that configure the outer circumference of the disposable diaper or the inner side in a widthwise direction from the diaper ends. A part of the waistline retaining unit is arranged in at least one of a first region in an outer side in the longitudinal direction from the ends of the leg stretching units, and a second region in an outer side in the widthwise direction from the ends of the leg stretching units. A joint region where the skin-surface side and non-skin surface side sheets are joined is provided along the diaper ends in at least one of a first region and a second region.

RELATED APPLICATIONS

The present application is a National Phase of International ApplicationNumber PCT/JP2013/062250, filed Apr. 25, 2013, which claims priority toJapanese Application Number 2012-103376, filed Apr. 27, 2012.

TECHNICAL FIELD

The present invention relates to a disposable diaper and a method ofmanufacturing a disposable diaper.

BACKGROUND ART

Conventionally, there is known a disposable diaper having: a frontwaistline region; a rear waistline region; a crotch region; a pair ofleg hole openings; an absorber running across the crotch region andextending to the front waistline region and rear waistline region; andleg stretching units stretching in a product longitudinal direction andarranged along the leg hole openings. The leg stretching units arearranged only near the leg hole openings and not in the entire region ofthe disposable diaper in longitudinal direction.

In Patent Literature 1, a method of manufacturing a disposable diaper inwhich the leg stretching units are arranged only near the leg holeopenings is disclosed. According to the method of manufacturing thedisposable diaper of Patent Literature 1, a first web configuring eitherone of the topsheet and the backsheet of the disposable diaper isconveyed in a continuous state, and an adhesive for pasting elasticmembers is applied near the leg hole openings of the first web (theportion where the leg stretching units are provided). The elasticmembers configuring the leg stretching units are elongated in theproduct longitudinal direction in a continuous state, and the elasticmembers in the elongated state are arranged on the first web.Subsequently, a second web configuring the other one of the topsheet andthe backsheet is pasted on the first web and the elastic members.

In this way, a continuous body of continuous first web, second web, andelastic members arranged between the two webs is manufactured. Next, thecontinuous body is cut along the product widthwise direction in each ofindividual product lengths. As a result, the elastic members in theelongated state are constricted in the product longitudinal direction,and only the portion that is pasted near the leg hole openings by theadhesive remains. Thus, the leg stretching units can be provided onlynear the leg hole openings.

CITATION LIST Patent Literature

-   [PTL 1] Japanese Patent Publication No. S57 (1982)-26219

SUMMARY OF INVENTION

However, the above-described disposable diaper had the below problems.

In the above-described disposable diaper, elastic members are pasted onthe web in an arrangement region of leg stretching units. However, inthe other regions, in order to shrink the elastic members after cuttingthe continuous body, the elastic members are not pasted on the web.Therefore, in the region where the elastic members are arranged in themanufacturing stage and the elastic members are not arranged in theproduct state, that is, in the outer side in the product longitudinaldirection or the outer side in the product widthwise direction from theleg stretching units, an adhesive cannot be applied on the first web andthe second web in order to set the leg stretching units in a shrinkablestate. Thus, the first web and the second web are not pasted in theproduct state on the outer side in the product longitudinal direction orthe outer side in the product widthwise direction from the legstretching units.

Furthermore, in the so-called tape-type disposable diaper, a fasteningtape is provided in the rear waistline region, and a target unit foraffixing the fastening tape is provided in the front waistline region.As a result of engagement between the fastening tape and the targetunit, the disposable diaper is retained along the waistline of thewearer. Thus, a pulling force works in the product widthwise directionon the fastening tape, the target unit, and a waistline retaining unitthat includes the region extending in the product widthwise directionfrom the fastening tape and the target unit.

The waistline retaining unit is arranged in the outer side in theproduct longitudinal direction or the outer side in the productwidthwise direction from the leg hole openings, and is the region wherethe topsheet and the backsheet may not be pasted together. Thus, sincethe topsheet and the backsheet of the waistline retaining unit are notpasted together, the force is applied only to one of the sheets at thetime of being pulled. For example, when a relatively high load isexerted, such as at the time of putting on or wearing the disposablediaper, a force that is stronger than the strength of one of the sheetsworks on the sheets because of which the sheets may tear.

Thus, the present invention has been achieved in view of the aboveproblems, and an object thereof is to provide a disposable diaper withwhich the strength of the waistline retaining unit that holds thewaistline of the wearer in a so-called tape-type disposable diaper isincreased, and the tearing at the time of putting on or wearing thediaper can be prevented, and also to provide a method of manufacturingsuch a disposable diaper.

The disposable diaper (disposable diaper 10) according to the presentdisclosure is summarized as a disposable diaper, including: a frontwaistline region (front waistline region 20); a rear waistlineregion(rear waistline region 30); a crotch region (crotch region 25)positioned between the front waistline region and the rear waistlineregion; a product longitudinal direction(product longitudinal directionL) from the front waistline region towards the rear waistline region,and a product widthwise direction (product widthwise direction W)perpendicular to the product longitudinal direction; a skin-surface sidesheet (skin-surface side sheet 50) arranged at a skin contact surfaceside of a wearer; a non-skin surface side sheet (non-skin surface sidesheet 51) arranged at a non-skin contact surface side of theskin-surface side sheet; an absorber (absorber 40) arranged between theskin-surface side sheet and the non-skin surface side sheet, runningacross the crotch region, and extending from the crotch region to atleast either one of the front waistline region and rear waistlineregion; a waistline retaining unit holding the disposable diaper ontothe body of the wearer in the front waistline region and the rearwaistline region; and leg stretching units (leg stretching unit 75)arranged along leg hole openings (leg hole opening 35) provided in anouter side in the product widthwise direction from the absorber andexpand and contract along the product longitudinal direction, whereinthe leg stretching units are arranged between the skin-surface sidesheet and the non-skin surface side sheet, and are arranged in the innerside in the product longitudinal direction from diaper ends thatconfigure the outer circumference of the disposable diaper or the innerside in the product widthwise direction from the diaper ends in a planview, and a part of the waistline retaining unit is arranged in at leastone of a first region (first region R1) in an outer side in the productlongitudinal direction from the ends of the leg stretching units in theproduct longitudinal direction, and a second region (second region R2)in an outer side in the product widthwise direction from the ends of theleg stretching units in the product longitudinal direction, and a jointregion (joint region 65) where the skin-surface side sheet and thenon-skin surface side sheet are joined is provided along the diaper endsin at least one of a first region and a second region .

The method of manufacturing a disposable diaper according to the presentdisclosure is summarized as method of manufacturing a disposable diaper,including: a front waistline region, a rear waistline region, a crotchregion positioned between the front waistline region and the rearwaistline region; a product longitudinal direction from the frontwaistline region towards the rear waistline region, and a productwidthwise direction perpendicular to the product longitudinal direction;a skin-surface side sheet arranged at a skin contact surface side of thewearer; and a non-skin surface side sheet arranged at a non-skin contactsurface side of the topsheet; and an absorber arranged between theskin-surface side sheet and the non-skin surface side sheet, runningacross the crotch region, and extending from the crotch region to atleast either one of the front waistline region and rear waistlineregion; and leg stretching units arranged along leg hole openingsprovided in an outer side in the product widthwise direction from theabsorber and can expand and contract along the product longitudinaldirection, the method comprising: a step of continuously conveying afirst web that configures either one of the skin-surface side sheet andthe non-skin surface side sheet; a step of elongating, the elasticmembers configuring the leg stretching units, in a continuous state, inthe product longitudinal direction; a step of cutting, the elasticmembers that are in the elongated state, along the product widthwisedirection; a step of pasting, the elastic members that are in the cutstate, on the first web through an adhesive; and a step of affixing, asecond web that configures the other one of the skin-surface side sheetand the non-skin surface side sheet, on the first web and the elasticmembers through an adhesive.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an exploded plan view of a disposable diaper according to thepresent embodiment.

FIG. 2 is an exploded plan view of the disposable diaper according tothe present embodiment.

FIG. 3 is a cross-sectional view of the disposable diaper along an F1-F1line shown in FIG. 1.

FIG. 4 is a cross-sectional view of the disposable diaper along an F2-F2line shown in FIG. 1.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment of a disposable diaper according to thepresent invention is described with reference to accompanying drawings.In the following description of the drawings, the same or similarreference numerals are used to designate the same or similar portions.It will be appreciated that the drawings are schematically shown and theratio and the like of each dimension are different from the real ones.

Therefore, a specific dimension should be determined in view of thefollowing description. Moreover, among the drawings, the respectivedimensional relations or ratios may differ.

(1) Overall Schematic Configuration of Disposable Diaper

FIG. 1 and FIG. 2 are exploded plan views of a disposable diaper 10according to the present embodiment. FIG. 3 is a cross-sectional view ofthe disposable diaper 10 along an F1-F1 shown in FIG. 1. FIG. 4 is across-sectional view of the disposable diaper 10 along an F2-F2 lineshown in FIG. 1. It should be noted that the exploded plan view of FIG.1 and FIG. 2 are diagram in which leg gathers 75 and leg side gathers 80are in an expanded state such that wrinkles are not formed in a topsheet50 and sidesheets 52, for example, that configure the disposable diaper10, but for the sake of description, the leg side gathers 80 areillustrated in a contracted state.

The disposable diaper 10 includes a front waistline region 20, a crotchregion 25, and a rear waistline region 30. The front waistline region 20is a portion that is in contact with the front waistline (ventralportion) of the wearer. Furthermore, the rear waistline region 30 is aportion that is in contact with the back waistline (dorsal portion) ofthe wearer. The crotch region 25 is positioned between the frontwaistline region 20 and the rear waistline region 30. Furthermore, apair of leg hole openings 35 are formed in the disposable diaper 10. Theleg hole openings 35, which are provided at the side ends in the productwidthwise direction of the disposable diaper, are the portions that arearranged to fit around the legs of the wearer when the disposable diaperis worn by the wearer.

In the present embodiment, the direction from the front waistline region20 to the rear waistline region 30 is called a product longitudinaldirection L, and the direction perpendicular to the product longitudinaldirection L is called a product widthwise direction W.

The disposable diaper 10 includes an absorber 40 running across thecrotch region 25 and extending from the crotch region 25 towards atleast one of the front waistline region 20 and the rear waistline region30. The absorber 40 is configured by an absorbent core 40 a and a corewrap 40 b.

The absorbent core 40 a is the same as in the conventional disposablediaper, and can be configured appropriately by using popular componentsand materials, such as ground pulp and high absorbent polymer. Theabsorbent core 40 a is wrapped by the sheet-like core wrap 40 b. Thecore wrap 40 b is a sheet for wrapping the absorbent core 40 a. A partof at least the skin surface side of the core wrap 40 b is configured byvarious nonwoven fabric or a tissue sheet having permeability. Forexample, an air-through nonwoven cloth, a spunbond nonwoven cloth, or anSMS (spunbond-meltblown-spunbond) nonwoven cloth having a mass ofapproximately 10 to 30 g/m², or a tissue sheet having a mass ofapproximately 10 to 30 g/m² can be used.

On the top side (skin contact surface side) of the absorber 40 isprovided a skin-surface side sheet 50. The skin-surface side sheet 50includes a liquid-permeable topsheet 51 and hydrophobic side sheets 52.The topsheet 51 is arranged to cover almost the entire absorber 40. Theside sheets 52 are arranged to cover the side units in the productwidthwise direction of the absorber 40 and the topsheet 51. Theskin-surface side sheet may not necessarily be configured by the twolayers of the topsheet 51 and the side sheets 52, may be configured byeither of the two sheets, and with including the other sheet.

On the back side (non-skin contact surface side) of the absorber 40 isprovided a liquid-impermeable non-skin surface side sheet 60. Thenon-skin surface side sheet 60 includes an exterior sheet 61 configuringan outer surface of the disposable diaper at the time of wearing, and abacksheet 62 arranged between the absorber 40 and the exterior sheet 61.The non-skin surface side sheet may not necessarily be configured by theexterior sheet 61 and the backsheet 62, and may be configured by eitherof the two sheets, and with including the other sheet.

The skin-surface side sheet 50 and the non-skin surface side sheet 60are joined by a hot-melt adhesive 76 (see FIG. 4). A joint region 65(see FIG. 2) in which the skin-surface side sheet 50 and the non-skinsurface side sheet 60 are joined is provided in the disposable diaper10. The joint region 65 will be described later in detail.

The side sheets 52 are provided in each of the side edges in the productwidthwise direction W of the absorber 40. The side sheets 52 areconfigured by one layer of nonwoven fabric or two or more plurality oflayers of nonwoven fabric layered on each other. Furthermore, afastening tape 90 is provided in each of the pair of side sheets 52.

The fastening tape 90 extends along the product widthwise direction W inthe rear waistline region 30, and holds the disposable diaper 10 ontothe body of the wearer when affixed on the non-skin contact surface ofthe front waistline region 20.

In the present embodiment, a waistline retaining unit is configured bythe front waistline region 20, the rear waistline region 30, and thefastening tape 90. The waistline retaining unit of the rear waistlineregion 30 is the range extending in the widthwise direction from theregion provided with an engagement member of the fastening tape 90. Thewaistline retaining unit of the front waistline region 20 is the rangeextending in the widthwise direction from the region provided with atarget unit 95.

The waistline retaining unit is arranged in the outer side in theproduct longitudinal direction from the leg stretching units 75. Forexample, if the leg stretching units overlap the waistline retainingunit, the waistline retaining unit is constricted by the leg stretchingunits in the product longitudinal direction, and the waistline retainingunit might shift in the product longitudinal direction. However, as thewaistline retaining unit is arranged in the outer side in the productlongitudinal direction from the leg stretching units and there is nooverlapping between the two, the shifting of the waistline retainingunit by the leg stretching units can be prevented.

The leg stretching units 75 are arranged in the outer side of thewidthwise direction from the absorber 40. The leg stretching units 75are arranged on the circumference of the leg hole openings 35, and areconfigured to be stretchable in the product longitudinal direction L.

Additionally, inside the pair of leg stretching units 75 (closer to thecenter in the product widthwise direction W), a pair of leg side gathers80 extending along the product longitudinal direction L are provided.The leg side gathers 80, which are provided in the inner ends in theproduct widthwise direction of the side sheets 52, are uprightstretching gathers arranged in the inner side in the product widthwisedirection from the leg stretching units. The leg side gathers 80 arearranged in the inner side in the product widthwise direction from theleg stretching units 75, and function as the leg side stretching units.

The side sheets 52 are folded back at the topsheet side in the innerends in the product widthwise direction, and are formed by laminatingtwo layers. Elastic members 71 (see FIG. 3) elongated in thelongitudinal direction are provided between the two layers of the sidesheets 52. The upright leg side gathers 80 are formed by the side sheets52 and the elastic members 71.

The exploded plan view of the disposable diaper shown in FIG. 1 is thestate in which the elastic members 71 of the leg side gathers 80 are ina contracted state, and the exploded plan view of the disposable diapershown in FIG. 2 illustrates the state in which the elastic members 71 ofthe leg side gathers 80 are in an elongated state.

The leg side gathers 80 include a joint portion 81 that is joined witheither the topsheet 51, or the backsheet 62 and the exterior sheet 61,and a free end portion 82 in which the elastic members are arranged. Inthe free end portion 82, the central portion in the longitudinaldirection that includes the crotch region 25 configures a contractionportion 84 that is constricted in the product longitudinal direction bythe elastic members 71. As for the leg side gathers 80, when the diaperis worn, the joint portion 81 rises up as the proximal end and thecontraction portion 84 of the free end portion 82 is in contact with theskin of the wearer as the apex. That is, the joint portion is theproximal end of the rise of the leg side stretching units.

The contraction portion 84 is the portion that is substantiallyconstricted in the product longitudinal direction by the elastic members71, and excludes the portion in which the elastic members 71 arearranged in a state in which the shrinkage force is not exhibited.Furthermore, in FIG. 2, the joint portions 81 in which the side sheets52 and the topsheet 50, or the backsheet 62 and the exterior sheet 61are joined in the leg side gathers are marked with slanting lines andillustrated.

Multiple joint portions 81 are provided, and while a first joint portion81A is arranged in the outer side in the product longitudinal directionfrom the contraction portion 84, a second joint portion 81B is arrangedin the outer side in the product widthwise direction from thecontraction portion 84. Thus, in the leg side gathers 80, the centralportion in the product longitudinal direction that includes the crotchregion 25 is configured to rise up at the side of the wearer.

Of the joint portions 81 of the leg side gathers 80, the second jointportion 81B that is arranged in the outer side in the product widthwisedirection from the contraction portion 84 is arranged in the inner sidein the product widthwise direction from the leg stretching units 75 inthe product widthwise direction W. The second joint portion 81B isjoined with the exterior sheet 61 through the backsheet 62 and a partthereof, in the entire length in the product longitudinal direction. Thebacksheet 62 is arranged between the absorber 40 and the exterior sheet61, and functions as a leakage-preventing sheet.

Of the joint portions 81 of the leg side gathers 80, the first jointportion 81A that is arranged in the outer side in the productlongitudinal direction from the contraction portion 84 is joined withthe topsheet 51.

The joint portions 81 of the leg side gathers 80 can have differenttypes of configurations. The joint portions, for example, extend in thefront waistline region and the rear waistline region from the inner legunit in the product longitudinal direction, and are configured to be anupright proximal end that may be the portion joined with the topsheet,or the portion joined with the backsheet and the exterior sheet in theouter side of the widthwise direction from the absorbent core 40 a.

Furthermore, the configuration of the leg side gathers is not limited tothe above configuration as long as the leg side gathers are uprightgathers arranged in the inner side in the product widthwise directionfrom the leg stretching units, and a configuration of the conventionallywell-known leg side gathers can surely be adopted.

Furthermore, a waist stretching unit 85 is provided between the pair offastening tapes in the product widthwise direction and can expand andcontract in the product widthwise direction. The waist stretching unit85 is arranged between the pair of fastening tapes in a plan view andshrinks the space between the fastening tapes in the widthwisedirection. The waist stretching unit 85 is arranged on the surface atthe skin contact surface side of the topsheet and shrinks the spacebetween the fastening tapes along the product widthwise direction W.

In the present embodiment, the waist stretching unit 85 is configured bya stretchable sheet. The member configuring the waist stretching unit 85is not particularly restricted, but a member that is as thin as possiblewith a low bending rigidity, and has a small reduction in width ispreferably used.

In the present embodiment, a stretch film having a basis weight of 20 to45 g/m² is used as the waist stretching unit 85.

After being extended up to 1.5 to 2.5 times the length in thenon-elongated state (natural state), the waist stretching unit 85 isadhered onto the exterior sheet 61 with a hot-melt adhesive or heatprocessing.

In the present embodiment, the waist stretching unit 85 is arrangedbetween the backsheet 62 and the exterior sheet 61. However, in the caseof a configuration in which the core wrap 40 b extends in the outer sidein the product longitudinal direction from the absorbent core 40 a, thewaist stretching unit 85 may be arranged between the core wrap 40 b andthe backsheet 62 or exterior sheet 61. The position of the waiststretching unit is not particularly restricted, however, the waiststretching unit is preferably arranged at the non-skin contact surfaceside from the absorber 40. Furthermore, in the region in which theabsorber is not arranged, the waist stretching unit may be arrangedbetween the side sheets 52 and the backsheet 62 or exterior sheet 61.

The waist stretching unit according to the present embodiment isconfigured to stretch in the product widthwise direction, however, thewaist stretching unit may be configured to stretch in the productwidthwise direction and the product longitudinal direction.

(2) Leg Stretching Units

Next, the leg stretching units 75 will be described in detail. The legstretching units 75 are arranged along the leg hole openings 35 providedin the outer side in the product widthwise direction from the absorber40, and are configured to be stretchable in the product longitudinaldirection L. In a plan view, the leg stretching units 75 are arranged inthe inner side in the product longitudinal direction from the diaperends that configure the outer circumference of the disposable diaper.

The diaper ends specifically imply front ends 10F of the disposablediaper, back ends 10R of the disposable diaper, and ends 10W in theproduct widthwise direction of the disposable diaper. The configurationof the present embodiment according to which the leg stretching units 75are positioned in the inner side in the product longitudinal directionfrom the diaper ends implies the configuration according to which theleg stretching units 75 are positioned in the inner side in the productlongitudinal direction from the front ends 10F and the back ends 10R ofthe disposable diaper.

Furthermore, for example, when the ends in the in the direction ofexpansion and contraction of the leg stretching units 75 extend in theproduct widthwise direction, the leg stretching units 75 are configuredto be positioned in the inner side in the product widthwise directionfrom the diaper ends. Specifically, the leg stretching units 75 areconfigured to be positioned in the inner side in the product widthwisedirection from the ends 10W in the product widthwise direction of thedisposable diaper.

The leg stretching units 75 thus configured are arranged only at thenecessary locations, such as near the leg hole openings 35, rather thanbeing arranged in the entire region of the diaper. Furthermore, in thecase of a configuration in which the leg stretching units 75 shrink inthe product longitudinal direction, the outer ends in the productwidthwise direction of the leg stretching units 75 may be aligned withthe ends in the widthwise direction, such as the side sheets that formthe leg hole openings 35. In addition, in the case of a configuration inwhich the leg stretching units 75 shrink in the product widthwisedirection, the outer ends in the product longitudinal direction of theleg stretching units 75 may be aligned with the ends in the longitudinaldirection, such as the side sheets that form the diaper ends.

The leg hole openings 35 and the leg stretching units 75 include aninner end region 751 in the widthwise direction that is positioned atthe innermost side in the crotch region in the widthwise direction, andextend in the outer side in the product widthwise direction from thecrotch region 25 towards the outer side in the product longitudinaldirection. It must be noted that the inner end region 751 in thewidthwise direction of the leg stretching units 75 may be arranged incontinuation in the product longitudinal direction, or may not be incontinuation in the product longitudinal direction.

The leg stretching units 75 according to the present embodiment areconfigured by a stretchable sheet. For example, a stretch film formed bymelting a thermoplastic elastomer resin, such as urethane and styrene,and then converting into the shape of a film, a stretchable nonwovenfabric formed from such stretchable fibers, or a composite sheet formedby pasting together inextensible sheets that have been partially cutinto a stretch film and stretchable nonwoven fabric, or have been madefragile can be used as the stretchable sheet.

Furthermore, rather than the stretchable sheet, the leg stretching units75 may be configured by arranging one or a plurality of thread-like orband-like elastic members made of polyurethane elastic fibers andnatural rubber.

The leg stretching units 75 are arranged between the skin-surface sidesheet 50 and the non-skin surface side sheet 60. Specifically, the legstretching units 75 are arranged between the side sheets 52 and theexterior sheet 61. Alternatively, in the region provided with thebacksheet 62 that is arranged between the absorber 40 and the exteriorsheet 61, the leg stretching units 75 are arranged between the backsheet62 and the side sheets 52.

At least in the crotch region 25, the stretchable sheet configuring theleg stretching units 75 is preferred to have a width of 5 mm (width inthe product widthwise direction W in the natural state of the disposablediaper 10) or more and 45 mm or less, or more preferably a width of 12.5mm or more and 35 mm or less. When the width is less than 5 mm, theeffect of lowering of the load on the skin by the elastic elementsachieved by substantially running, in the form of a surface of thestretchable sheet, along the area around the legs of the wearer so as toprevent the partial concentration of the securing force is notexhibited, and when the width exceeds 45 mm, the region along the areaaround the legs becomes too wide in comparison to the length in theproduct widthwise direction of the entire disposable diaper, and as aresult, the stretchable sheet might become entangled at the side of thewearer's body, or may turn over.

The ratio of expansion and contraction of the leg stretching units 75 ispreferably 1.5 times to 2.3 times. In the present embodiment, the ratioof expansion and contraction of the leg stretching units 75 is set to1.8 to 2.0 times. It should be noted that the ratio of expansion andcontraction implies the extent of elongation of the leg stretching unitsand is stipulated as below.Ratio of expansion and contraction=(Length of the leg stretching unitsin the elongated state)÷(Length of the leg stretching units in thenatural state)

It should be noted that the ratio of expansion and contraction as usedherein is to be measured as described below, for example.

Firstly, if the disposable diaper 10 is inserted in a package, forexample, then the disposable diaper 10 is taken out of the package, andthe diaper is kept in such a condition for 60 minutes under anatmosphere having a temperature of 20° C.±2° C., and a relative humidityof 60%±5% RH, and the length of the leg stretching units is measuredalong the in the direction of expansion and contraction. This length isthe “Length of the leg stretching units in the natural state”.

Secondly, the length in the in the direction of expansion andcontraction of the desired region of the open-type disposable diaper inthis state (that is, in the natural state), and the length in the in thedirection of expansion and contraction of the desired region, when theopen-type disposable diaper is extended from its natural state untilwrinkles caused by the elastic members are not visible, are measured.This length is the “Length of the leg stretching units in the elongatedstate”.

The ratio of expansion and contraction is measured by using thesemeasurement results and calculating according to the formula describedabove.

Additionally, it is preferable to measure the length in each of theabove-described states along the lines at the ends inside in the productwidthwise direction of the leg stretching units when the leg stretchingunits are curved as in the present embodiment.

Furthermore, the interval between the inner ends of the pair of theleft-right leg stretching units 75 in the product widthwise direction Wwidens from the crotch region 25 towards the front waistline region 20,and also widens from the crotch region 25 towards the rear waistlineregion 30. When the diaper is worn on the body of the wearer, if the legstretching units are arranged in a shape that is narrow in the crotchand broadens towards the front and back waistline, the leg stretchingunits can be brought closer along the line of the body, and the legstretching units are elongated and arranged favorably in the area aroundthe legs of the wearer.

Additionally, the interval (D1 in the figure) between the ends of thefront waistline region 20 of the pair of left-right leg stretching units75 is narrower than the interval (D2 in the figure) between the ends ofthe rear waistline region 30 of the pair of left-right leg stretchingunits 75. The interval is the distance between the inner ends of thepair of left-right leg stretching units 75 in the product widthwisedirection W that is measured after expanding and holding the disposablediaper 10 from the natural state to the state when no wrinkles areformed, in the product longitudinal direction L and the productwidthwise direction W.

The extension of the skin surface of the body of the wearer isparticularly large in the hip, and is remarkable at a position towardsthe outer widthwise direction. Furthermore, the leg stretching units 75are in contact with the body of the wearer. Because D2>D1, even when themovement of the wearer is added to the disposable diaper 10, the legstretching units 75 in the hip can extend while being in contact withthe body, and even when the amount of change of the stretching is large,the leg stretching units 75 do not become stiff. Therefore, the shiftingof the disposable diaper 10 by the leg stretching units 75 can becontrolled.

Furthermore, the leg hole openings 35 and the leg stretching units 75have a curved shape that extends in the outer side in the productwidthwise direction from the crotch region 25 towards the outer side inthe product longitudinal direction, and the distance between the innerends in the product widthwise direction at the ends in the productlongitudinal direction of the leg stretching units 75 and the inner endsin the product widthwise direction in the crotch region of the legstretching units is 3 mm or more and 35 mm or less.

Specifically, as shown in FIG. 2 a distance D3 between inner ends 75RWin the product widthwise direction at the back ends of the legstretching units, and inner ends 75CW in the product widthwise directionat the portion positioned in the innermost side of the widthwisedirection of the leg stretching units, or a distance D4 between innerends 75FW in the product widthwise direction at the front ends of theleg stretching units, and the inner ends 75CW in the product widthwisedirection at the portion positioned in the innermost side of thewidthwise direction of the leg stretching units is 3 mm or more and 35mm or less.

It should be noted that as long as the leg hole openings 35 areconfigured to be stretchable in the product longitudinal direction, theleg stretching units 75 may be arranged along the leg hole openings 35,a part of the leg stretching units may be arranged at a slant withrespect to the leg hole openings 35, or a part of the leg stretchingunits may be spaced apart from the leg hole openings 35. Specifically,the distance between the leg hole openings 35 and the leg stretchingunits 75 in the product widthwise direction is desired to be 7 mm orless. This is because when the distance between the leg hole openings 35and the leg stretching units 75 in the product widthwise direction is 7mm or less, the stretching force of the leg stretching units 75 issubstantially transferred up to the leg hole openings 35, and the diapercan be affixed on the wearer up to the ends of the leg hole openings 35.

It should be noted that the leg stretching units 75 correspond to theportion that is substantially constricted in the product longitudinaldirection by the stretchable sheet and the thread-like elastic members,and exclude the portion in which the stretchable sheet is arranged in astate in which the contraction force is not exhibited.

(3) Configuration of Joint Region

Next, the joint region 65 will be described. The joint region 65 is theregion where the skin-surface side sheet 50 and the non-skin surfaceside sheet 60 are joined by a hot-melt adhesive, or the like. In FIG. 2,the joint region 65 is illustrated by adding slanting lines. The jointregion 65 illustrated in FIG. 2 is the region in which the skin-surfaceside sheet 50 and the non-skin surface side sheet 60 are pasteddirectly.

The joint region 65 is arranged at least in a first region (see FIG. 1)R1 in the outer side in the product longitudinal direction from the endsin the product longitudinal direction of the leg stretching units, and asecond region (see FIG. 1) R2 in the outer side in the product widthwisedirection from the ends in the product longitudinal direction of the legstretching units.

In the first region R1 and the second region R2, the joint region 65where the skin-surface side sheet 50 and the non-skin surface side sheet60 are joined is provided in continuation along the diaper ends.Specifically, in the first region R1, the joint region 65 is provided incontinuation in the product widthwise direction along the front ends 10Fof the disposable diaper and the back ends 10R of the disposable diaper.Furthermore, in the second region R2, the joint region 65 is provided incontinuation in the product longitudinal direction along the ends 10W inthe product widthwise direction of the disposable diaper.

Furthermore, in the first region R1, a part of the waistline retainingunit, which is arranged inside the region extending along the productwidthwise direction from the fastening tape 90 and is arranged insidethe region extending along the product widthwise direction from thetarget unit 95, is arranged.

In this way, as the joint region 65 is provided in continuation alongthe diaper ends in the first region R1 and the second region R2, thestrength can be increased as compared to the configuration in whichsheets are not joined together. A part of the waistline retaining unitis arranged in the first region R1 and the second region R2, which formsthe region where force is exerted at the time of wearing the diaper. Byincreasing the strength of this region, the tearing of the sheets can beprevented when a relatively high load is exerted, such as at the time ofputting on or wearing the diaper.

Furthermore, in the entire disposable diaper, as seen in the plan view,the skin-surface side sheet 50 and the non-skin surface side sheet 60are joined with each other through another member (such as a fasteningtape). Thus, the joint region is substantially provided in continuationalong the diaper ends in the entire region of the disposable diaper.

Specifically, in the portion where the fastening tape is arranged, theskin-surface side sheet and the non-skin surface side sheet are pastedthrough the fastening tape, and in the portion where the absorber isarranged, the skin-surface side sheet and the non-skin surface sidesheet are pasted through the absorber, and furthermore, in the portionwhere the leg stretching units 75 are arranged, the skin-surface sidesheet and the non-skin surface side sheet are pasted through the legstretching units 75.

Because the joint region is arranged in the entire region of thedisposable diaper, the rigidity of the entire disposable diaper and thestrength of the disposable diaper can be increased. Furthermore, if thetopsheet and the backsheet are spaced apart in a part of the ends of thediaper, the user may feel that the product is defective, and may beconcerned about leakage from the portion where the topsheet and thebacksheet are spaced apart. However, as the joint region is provided inthe entire region of the disposable diaper, the disposable diaper can beworn by the wearer without any concerns.

The joint region is not only configured by the region where theskin-surface side sheet and the non-skin surface side sheet are joinedby direct contact, but also includes the configuration where theskin-surface side sheet and the non-skin surface side sheet are joinedthrough another member (such as a sheet). Furthermore, in the jointregion, the two layers of the skin-surface side sheet in the form of theside sheets or the topsheet, and the non-skin surface side sheet in theform of the backsheet or the exterior sheet may be joined together, or aplurality of layers of the skin-surface side sheet, and a plurality oflayers of the non-skin surface side sheet may be joined together. Inaddition, the joint region may be the region where the sheets are joinedtogether by a hot-melt adhesive, or may be a region where joining isperformed by another joining method such as heat welding, etc.

(4) Method of Manufacturing the Disposable Diaper

Next, an example of the method of manufacturing the disposable diaperaccording to the present embodiment will be described. As far as themethod that is not described in the present embodiment is concerned, theexisting method can be used. Furthermore, the manufacturing methodexplained below is only an example, and the disposable diaper can alsobe manufactured by other manufacturing methods. The method ofmanufacturing the disposable diaper includes at least a componentforming step, a component loading step, a leg hole forming step, and acutting step.

In the component forming step, the components configuring the disposablediaper are formed. Specifically, for example, an absorbent material islaminated and the absorber 40 is molded.

The component loading step includes loading on a first web, whichconfigures one of the skin-surface side sheet and the non-skin surfaceside sheet, the components configuring the disposable diaper, such asthe stretchable sheet that configures the leg stretching units 75, thesecond web that configures the other one of the skin-surface side sheetand the non-skin surface side sheet, etc.

More specifically, a step of continuously conveying a first web, a stepof elongating the elastic members configuring the leg stretching unitsin a continuous state, in the product longitudinal direction, a step ofcutting the elastic members that are in the elongated state along theproduct widthwise direction, a step of pasting the elastic members thatare in the cut state on the first web through an adhesive, and a step ofaffixing the second web on the first web and the elastic members throughan adhesive are included.

For example, the step of elongating the elastic members configuring theleg stretching units in a continuous state, in the product longitudinaldirection, and the step of cutting the same are implemented byelongating the stretchable sheet that configures the leg stretchingunits 75, transferring the stretchable sheet onto an intermittent drumwhile displacing in the widthwise direction, and then cutting thestretchable sheet in individual product lengths on the intermittentdrum. Furthermore, a gap is provided between the stretchable sheets as aresult of the rotation of the intermittent drum, and the stretchablesheets are transferred on a continuous web. At this time, thestretchable sheet and the web are affixed by applying an adhesivebeforehand either on the stretchable sheet or the web. Next, another webis affixed to the web on which the stretchable sheet has been affixed.At this time, by applying an adhesive on at least any one of the firstweb or the second web, the first web, the stretchable sheet, and thesecond web can be joined together as one part.

It should be noted that if the adhesive is to be applied on both thefirst web and the second web, it is desirable to have different adhesionpatterns for the first web and the second web. Generally, when applyingthe adhesive, an interval is provided such as by applying the adhesivein helices or dots. At this time, for example, if the pattern ofapplying the adhesive on the first web and the second web is the same,then when the non-joint portions, where an adhesive is not applied, arealigned, the non joint portions will be aligned at several locations asthe non-joint portions are also arranged at the same interval. Thiswould lead to the presence of several non joint portions.

However, by changing the pattern of application of the adhesive on thefirst web and the second web, even when the non joint portions arealigned in one part, the alignment of the non joint portions at severallocations can be prevented as the non-joint portions are arranged at adifferent interval. Thus, skipping of the leg stretching units in thenon joint portions, and isolation of sheets can be prevented.

In the leg hole forming step, the first web that configures theskin-surface side sheet 50 and the second web exterior sheet thatconfigures the non-skin surface side sheet 60 are cut along the outerends of the widthwise direction of the leg stretching units 75. The leghole openings 35 arranged in the area around the legs of the wearer arethus formed.

In the cutting step, the continuous body on which the topsheet 51, theexterior sheet 61, and the absorber 40 are arranged is cut in the sizeof one product along the product widthwise direction W. The disposablediaper 10 is thus manufactured.

According to such a manufacturing method, there is no need of providinga non-adhering portion for stretching the leg stretching units aftercutting the web as in the past, and therefore, the skin-surface sidesheet 50 and the non-skin surface side sheet 60 can be joined in thefirst region R1 and the second region R2 in the circumference of the legstretching units 75 while arranging the leg stretching units only nearthe leg hole openings 35. In comparison to the configuration where thesheets are not joined with each other, as in the past, the strength ofthe sheets can be increased. A part of the waistline retaining unit isarranged in the first region and the second region, and this is theregion where force is exerted at the time of wearing the diaper. Byincreasing the strength of this region, the tearing of the skin-surfaceside sheet 50 and the non-skin surface side sheet 60 at the time ofwearing the diaper can be prevented.

Furthermore, in the disposable diaper according to the modification,rather than leg gathers formed from an elastic nonwoven sheet, leggathers formed from thread-like elastic members may be provided.

(5) Operation and Effect

In the disposable diaper according to the present embodiment, the firstregion R1 and the second region R2 that are arranged in thecircumference of the ends in the in the direction of expansion andcontraction of the leg stretching units 75 can be joined when the legstretching units 75 are arranged only near the leg hole openings 35.Therefore, in comparison to the configuration where the sheets are notjoined with each other, the strength of the sheets can be increased. Apart of the waistline retaining unit is arranged in the first region andthe second region, and this is the region where force is exerted at thetime of wearing the diaper. By increasing the strength of this region,the tearing of the skin-surface side sheet and the non-skin surface sidesheet at the time of wearing the diaper can be prevented.

Furthermore, the skin-surface side sheet and the non-skin surface sidesheet are substantially joined in the entire region of the disposablediaper. Thus, the rigidity of the entire disposable diaper can beimproved. Furthermore, if the skin-surface side sheet and the non-skinsurface side sheet are spaced apart in a part of the ends of the diaper,the user may feel that the product is defective. However, as the jointregion is provided in the entire region of the disposable diaper, thedisposable diaper can be worn by the wearer without any concerns.

The skin-surface side sheet 50 arranged in the first region R1 and thesecond region R2 can be configured only by a nonwoven fabric having abasis weight of 15 g/m² or less. The strength of the disposable diaper10 according to the present embodiment can be increased by joining theskin-surface side sheet 50 and the non-skin surface side sheet 60. Thus,the skin-surface side sheet 50 can be configured only by a nonwovenfabric, without including a film such as a leakage-preventing filmhaving a relatively high rigidity. By configuring the skin-surface sidesheet 50 only by a nonwoven fabric, and by being able to reduce thebasis weight of the nonwoven fabric, the feel on the skin can be madesofter and the air permeability of the corresponding part can beimproved. It should be noted that the non-skin surface side sheet 60 maybe configured only by a nonwoven fabric.

(6) Other Embodiments

As described above, the present invention is disclosed through the aboveembodiments of the present invention. However, it should not beinterpreted that the statements and drawings constituting a part of thepresent disclosure limit the present invention. From this disclosure, avariety of alternate embodiments, examples, and applicable techniqueswill become apparent to one skilled in the art.

For example, in the method of manufacturing the disposable diaper, thestep of elongating the cut elastic members in the product longitudinaldirection may be performed after the step of cutting the elastic membersconfiguring the leg stretching units along the product widthwisedirection.

As described above, it is of course that the present invention includesvarious embodiments and the like not described here. Therefore, thetechnical range of the present invention is to be defined only by theinventive specific matter according to the adequate claims from theabove description.

The entire contents of Japanese Patent Application No. 2012-103376(filed on Apr. 27, 2012) are incorporated in the present specificationby reference.

INDUSTRIAL APPLICABILITY

It is possible to provide a disposable diaper with which the strength ofthe waistline retaining unit that holds the waistline of the wearer in aso-called tape-type disposable diaper is increased, and the tearing atthe time of putting on or wearing the diaper can be prevented, and alsoto provide a method of manufacturing such a disposable diaper.

REFERENCE SIGNS LIST

-   10 . . . Disposable diaper-   10F . . . Front end-   10R . . . Back end-   10W . . . Ends in the product widthwise direction-   20 . . . Front waistline region-   25 . . . Crotch region-   30 . . . Rear waistline region-   35 . . . Leg hole opening-   40 . . . Absorber-   40 a . . . Absorbent core-   40 b . . . Core wrap-   50 . . . Skin-surface side sheet-   51 . . . Topsheet-   52 . . . Side sheet-   60 . . . Non-skin surface side sheet-   61 . . . Exterior sheet-   62 . . . Backsheet-   65 . . . Joint region-   71 . . . Elastic member-   75 . . . Leg stretching unit-   75I . . . Inner end region in the widthwise direction of the leg    stretching units-   80 . . . Leg side gather-   81 . . . joint portion-   81A . . . First joint portion-   81B . . . Second joint portion-   82 . . . Free end portion-   84 . . . Contraction portion-   85 . . . Waist stretching unit-   90 . . . Fastening tape-   95 . . . Target unit-   L . . . Product longitudinal direction-   W . . . Product widthwise direction-   R1 . . . First region-   R2 . . . Second region

The invention claimed is:
 1. A disposable diaper, comprising: a frontwaistline region, a rear waistline region, a crotch region positionedbetween the front waistline region and the rear waistline region; aproduct longitudinal direction from the front waistline region towardsthe rear waistline region, and a product widthwise directionperpendicular to the product longitudinal direction; a skin-surface sidesheet adapted to face toward a body of a wearer when the diaper is worn;a non-skin surface side sheet adapted to face away from the body of thewearer when the diaper is worn; an absorber arranged between theskin-surface side sheet and the non-skin surface side sheet, runningacross the crotch region in the product longitudinal direction, andextending from the crotch region to at least either one of the frontwaistline region and rear waistline region; a waistline retaining unitdisposed in the front and rear waistline regions and adapted to hold thedisposable diaper onto the body of the wearer; leg stretching unitsarranged along leg hole openings provided on an outer side of theabsorber in the product widthwise direction, said leg stretching unitbeing configured to expand and contract along the product longitudinaldirection; and diaper ends defining an outer circumference of thedisposable diaper, wherein the leg stretching units are arranged betweenthe skin-surface side sheet and the non-skin surface side sheet, in aplan view of the disposable diaper, the leg stretching units arearranged on an inner side of the diaper ends in the product longitudinaldirection or on the inner side of the diaper ends in the productwidthwise direction, the leg stretching units have ends opposing eachother in the product longitudinal direction, a part of the waistlineretaining unit is arranged in at least one of a first region on an outerside in the product longitudinal direction from the ends of the legstretching units, or a second region on an outer side in the productwidthwise direction from the ends of the leg stretching units, a jointregion where the skin-surface side sheet and the non-skin surface sidesheet are joined is provided along the diaper ends in at least one ofthe first region or the second region, a first adhesive is applied at aninterval, on the skin-surface side sheet of the first region and thesecond region, based on a first application pattern, and a secondadhesive is applied at an interval, on the non-skin surface side sheetof the first region and the second region, based on a second applicationpattern different from the first application pattern.
 2. The disposablediaper according to claim 1, wherein the joint region is provided alongthe diaper ends in an entire area of the disposable diaper.
 3. Thedisposable diaper according to claim 1, wherein the skin-surface sidesheet and the non-skin surface side sheet arranged in the first regionand the second region are configured only by a nonwoven fabric.
 4. Thedisposable diaper according to claim 1, wherein at least any one of theskin-surface side sheet and the non-skin surface side sheet isconfigured only by a nonwoven fabric having a basis weight of 15 g/m² orless.
 5. The disposable diaper according to claim 1, wherein the leghole openings and the leg stretching units have a curved shape thatextends outward in the product widthwise direction while extending fromthe crotch region towards the front and rear waistline regions in theproduct longitudinal direction, each of the leg stretching units hasfront and rear inner edges in the product widthwise direction at theends of the leg stretching unit, and an intermediate inner edge in theproduct widthwise direction in the crotch region, and a distance betweenthe first inner edge or the second inner edge and the intermediate inneredge in the product widthwise direction is 3 mm or more and 35 mm orless.
 6. The disposable diaper according to claim 1, wherein the legstretching units are band-shaped elastic members each having apredetermined width in the product widthwise direction, and the width ofeach of the elastic members in the product widthwise direction is 5 mmor more and 45 mm or less.
 7. The disposable diaper according to claim1, wherein the waistline retaining unit is arranged on the outer sidefrom the leg stretching units in the product longitudinal direction. 8.The disposable diaper according to claim 1, wherein the part of thewaistline retaining unit is arranged in (i) the first region on theouter side in the product longitudinal direction from the ends of theleg stretching units and (ii) the second region on the outer side in theproduct widthwise direction from the ends of the leg stretching units.9. The disposable diaper according to claim 8, wherein the joint regionwhere the skin-surface side sheet and the non-skin surface side sheetare joined is provided along the diaper ends in both of the first regionand the second region.
 10. A disposable diaper, comprising: a frontwaistline region, a rear waistline region, a crotch region positionedbetween the front waistline region and the rear waistline region; aproduct longitudinal direction from the front waistline region towardsthe rear waistline region, and a product widthwise directionperpendicular to the product longitudinal direction; a skin-surface sidesheet adapted to face toward a body of a wearer when the diaper is worn;a non-skin surface side sheet adapted to face away from the body of thewearer when the diaper is worn; an absorber arranged between theskin-surface side sheet and the non-skin surface side sheet, runningacross the crotch region in the product longitudinal direction, andextending from the crotch region to at least either one of the frontwaistline region and rear waistline region; a waistline retaining unitdisposed in the front and rear waistline regions and adapted to hold thedisposable diaper onto the body of the wearer; leg stretching unitsarranged along leg hole openings provided on an outer side of theabsorber in the product widthwise direction, said leg stretching unitbeing configured to expand and contract along the product longitudinaldirection; and diaper ends defining an outer circumference of thedisposable diaper, wherein the leg stretching units are arranged betweenthe skin-surface side sheet and the non-skin surface side sheet, in aplan view of the disposable diaper, the leg stretching units arearranged on an inner side of the diaper ends in the product longitudinaldirection or on the inner side of the diaper ends in the productwidthwise direction, the leg stretching units have ends opposing eachother in the product longitudinal direction, a part of the waistlineretaining unit is arranged in at least one of a first region on an outerside in the product longitudinal direction from the ends of the legstretching units, or a second region on an outer side in the productwidthwise direction from the ends of the leg stretching units, a jointregion where the skin-surface side sheet and the non-skin surface sidesheet are joined is provided along the diaper ends in at least one ofthe first region or the second region, a first adhesive is applied in afirst application pattern, on the skin-surface side sheet of the firstregion and the second region, and a second adhesive is applied in asecond application pattern, on the non-skin surface side sheet of thefirst region and the second region, the second application patterndifferent from the first application pattern.